The use of warfarin is rarely complicated by skin necrosis. We describe a 50-year-old woman who presented with a left leg deep venous thrombosis and subsequent pulmonary embolism. She was initially anticoagulated with low-molecular weight heparin and subsequently warfarin. Within 4 days abdominal skin necrosis developed. Investigations revealed the presence of protein S deficiency and in addition, a mutation in the methylenetetrahydrofolate reductase gene (MTHFR). We present, to our best knowledge, the first case of warfarin skin necrosis associated with a methylenetetrahydrofolate reductase mutation.